1. Field of the Invention
The present invention concerns a cell for treating a liquid medium by means of flotation.
It is applicable in particular, but not exclusively, to removing ink from the paper pulp and for treating paper mill residual water.
2. Description of the Prior-Art
The flotation ink-removal cells currently available on the market are of the type in which the paper pulp is projected into the cell by a set of injectors and rotates at a relatively high speed inside the cell. Fresh air is introduced by the injectors so as to create inside the cell air bubbles which shall make the ink particles rise.
These known type of ink-removal cells by means of flotation do have the drawback in that the dwell time of the paper pulp inside the cell is too short to obtain suitable ink removal. Furthermore, excessive agitation existing inside these cells causes flocculence resulting in the loss of fibres.
In known flotation residual water treatment systems, an air pressurisation sends air under pressure mixed with water into the flotation cell. The surface impurities are removed with the aid of a rotating bucket joined to the centre of the cell.
These known residual water treatment systems have the drawback in that the water circulation speed inside the cell is too high to enable the water to be effectively cleaned.
The present invention is able to resolve the above-mentioned drawbacks exhibited by the known treatment cells by a treatment cell acting by means of flotation which, by significantly reducing the circulation speed of the liquid medium to be treated inside the cell, is able to substantially improve the quality of treatment of this liquid medium.